Solution:
Concept- Here we solve them by putting the values directly into the formula and adding, multiplying, subtracting, and dividing the numbers.The formula given in the question is
Values given are 
By adjusting the value provided in the formula, we obtain-
By applying cross multiplication We get,
Moving an expression containing a variable to one side
By taking b common on right-hand side of the equation
Above Equation is divided by 2, then canceling out the same terms in denominator and numerator from both side of the equation gives:
Hence, the correct answer is option 2) 20
